Electro-Acoustic Sensors

ABSTRACT

Ultrasonic transmitting elements in an electroacoustical transceiver transmit acoustic energy to an electroacoustical transponder, which includes ultrasonic receiving elements to convert the acoustic energy into electrical power for the purposes of powering one or more sensors that are electrically coupled to the electroacoustical transponder. The electroacoustical transponder transmits data collected by the sensor(s) back to the electroacoustical transceiver wirelessly, such as through impedance modulation or electromagnetic waves. A feedback control loop can be used to adjust system parameters so that the electroacoustical transponder operates at an impedance minimum. An implementation of the system can be used to collect data in a vehicle, such as the tire air pressure.

RELATED APPLICATIONS

This application is continuation-in-part of U.S. patent application Ser.No. 14/671,741, entitled “Electro-Acoustic Device Charging and PowerSupply,” filed on Mar. 27, 2015, which claims priority to U.S.Provisional Application No. 61/971,204, entitled “Battery Charging orDirect Power Delivery,” filed on Mar. 27, 2014, which are herebyincorporated by reference.

TECHNICAL FIELD

This application relates to the transmission of electrical power betweenelectronic devices without the use of wires. More specifically, thepresent application pertains to the transmission of electrical power todirectly power a sensor, such as a sensor in a vehicle.

BACKGROUND

Portable devices such as mobile phones, laptop computers, tables, andother communication device primarily rely on electrical battery energyto operate and conduct communications. Electrical batteries storechemical energy and deliver electrical energy through an electrochemicalconversion process. Electrical batteries may be non-rechargeable orrechargeable. Although some portable devices may use non-rechargeablebatteries, the vast majority depend on rechargeable batteries.

To recharge, conventional power transfer into portable devices requiresthese devices to be plugged into an electrical outlet. Although wirelessdata transmission is commonplace, wireless power transmission is not,except at extremely low power levels and not in an effective form formany applications. One impediment to wireless power transmission is thediffusion and diffraction of electromagnetic waves which is theconventional wireless transmission of electrical power. Consequently,this spreads out the available energy so that only a tiny fraction isavailable at the receiving end.

Nevertheless, manufacturers have begun producing wireless batterycharging stations. They operate under the principle of electromagnetic(EM) induction. electromagnetic induction is well known in the art andinvolves coupling the magnetic field generated by an external coil withan implanted coil (Schuder, 1960; Van Schuylenbergh and Puers, 2009). Asthe name connotes, wireless charging pads recharge portable devicebatteries and forego the necessity of connecting wires.

Other disclosures, e.g., patent Pub. No. US 2013/0241468 A1 (Moshfeghi,2013) disclose battery charging using an array of transducers and apower combiner connected to a battery charger. These systems are costlyand difficult to manufacture and maintain and have other operationallimits with respect to the power and frequency range of their operation,which make them non-ideal for some applications as discussed below.

With the proliferation of wireless devices, electromagnetic interferenceamongst devices will become an increasing problem with electromagneticinduction charging. In general, electromagnetic waves are incoherent andtend to spread out spatially while propagating. Electromagnetic systemsalso depend on a progressively crowded frequency space shared with otherdevices. Both electromagnetic stray fields (noise) from diffusion andbandwidth encroachment can interfere with the operation of nearbydevices that are sensitive to such interference.

Although a useful method, electromagnetic induction charging has otherlimitations. To achieve sufficient power at the receiver, the powerlevel at the transmitter becomes impractically high. Additionally, tofocus a useable amount of energy to the transmitter requires physicallylarge antennas. This is due to the focusing antennas having to be manytimes larger than the wavelength of the transmitted radiation.

Furthermore, there is difficulty of controlling the impedance matchingas a function of transmitter and receiver alignment. That in turnreduces the efficiency of transmission, leading to heating of theelectronic devices themselves, causing, in some cases, their failure.There are also issues relating to safety and electromagneticinterference to other electronic devices.

Therefore, there exists a need for an electric power charging systemusing directional power propagation without the threat ofelectromagnetic interference and bandwidth infringement of otherdevices.

Other problems exist in the automotive industry. For example,underinflated automotive tires are the cause of many avoidableaccidents. Since manually checking the tire pressure is inconvenient, itis often neglected by the motorist. Several systems have been developedand deployed to automate this process, but they all have shortcomings.Indirect tire pressure monitoring systems (TPMSs) suffer inaccuracy andare plagued with a high percentage of false positives as well as falsenegatives. Direct TPMSs (DTPMs) require batteries that must be replacedat regular intervals and are prone to failure due to harsh environmentalconditions, such as vibration, shock and extreme temperatures.

Powering of TPMS sensors has been attempted using micro machined electromechanical systems (MEMS) embedded in the tire assembly with the TPMS.The powering of these MEMS units is based on energy harvesting resultingfrom the movement of the tires during the automobile's motion. However,these systems have proven to be unreliable as a powering source due tothe difficulty in harvesting useful power from relatively unpredictabletypes of motion during the automobile's movement. Examples of existingTPMSs are disclosed in U.S. Pat. No. 6,175,302, titled “Tire PressureSensor Indicator Including Pressure Gauges That Have a Self-GeneratingPower Capability,” U.S. Pat. No. 8,011,237, titled “Piezoelectric ModuleFor Energy Harvesting, Such As In a Tire Pressure Monitoring System,”and U.S. Pat. No. 9,484,522, titled “Piezoelectric Energy HarvesterDevice With Curved Sidewalls, System, And Methods Of Use And Making.”

Therefore, there exists a need for more accurate and more reliablesystems to automatically check tire pressure on vehicles.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with some aspects of the present invention asset forth in the present disclosure and claims.

SUMMARY

The following description and drawings set forth certain illustrativeimplementations of the disclosure in detail, which are indicative ofseveral exemplary ways in which the various principles of the disclosuremay be carried out. The illustrative examples, however, are notexhaustive of the many possible embodiments of the disclosure. Otherobjects, advantages and novel features of the disclosure will be setforth in the following detailed description of the disclosure whenconsidered in conjunction with the drawings.

An aspect of the invention is directed to a direct tire pressuremonitoring system for a vehicle. The direct tire pressure monitoringsystem comprises a stationary transceiver configured to be mounted on anon-rotating axle of a suspension system for a wheel on the vehicle, thestationary transceiver comprising: one or more electroacoustictransmitting elements; a signal generator; an amplifier; and a firstantenna. The direct tire pressure monitoring system also comprises amovable transponder configured to be mounted on a rim of the wheel, themovable transponder comprising: one or more electroacoustic receivingelements; a tire pressure sensor; and a second antenna. The first andsecond antennae are in electromagnetic communication and saidelectroacoustic transmitting and receiving elements are in ultrasoniccommunication.

In one or more embodiments, the stationary transceiver is configured tobe in electrical communication with a central processing unit of avehicle control system for the vehicle. In one or more embodiments,signals are generated by said signal generator and amplified by saidamplifier. In one or more embodiments, said amplified signals aretransmitted over said one or more electroacoustic transmitting elements,said one or more electroacoustic transmitting elements generatingacoustic energy that passes from said stationary transceiver to saidmoveable transponder via said non-rotating axle and said rim. In one ormore embodiments, said transmitted ultrasonic signals are received bysaid electroacoustic receiving elements. In one or more embodiments, themovable transponder converts said transmitted ultrasonic signals intoconverted electrical energy. In one or more embodiments, the tirepressure sensor and ancillary electronics are powered by said convertedelectrical energy. In one or more embodiments, the stationarytransceiver is configured to generate progressive longitudinal waves,shear waves, or a combination thereof of ultrasonic energy. In one ormore embodiments, the stationary transceiver is configured to generate astanding wave of ultrasonic energy. In one or more embodiments, ahigh-energy node of the standing wave is disposed at the movabletransponder.

Another aspect of the invention is directed to a method for directlymonitoring tire pressure in a vehicle, the method comprising: generatingultrasound energy with a stationary transceiver mounted on anon-rotating axle of a suspension system for a wheel in the vehicle;receiving the ultrasound energy with an electroacoustic receivingelement in a movable transponder mounted on the wheel; in the movabletransponder, converting the ultrasound energy into converted electricalenergy; and with a tire pressure sensor coupled to the movabletransponder, monitoring the tire pressure of a tire mounted on thewheel, the tire pressure sensor receiving at least some of the convertedelectrical energy.

In one or more embodiments, the method further comprises generating astanding wave of the ultrasound energy with the stationary transceiver.In one or more embodiments, the method further comprises aligning ahigh-energy node of the standing wave of the ultrasound energy with alocation of the movable transponder. In one or more embodiments, themethod further comprises wirelessly transmitting tire pressure data fromthe movable transponder to the stationary transceiver. In one or moreembodiments, the tire pressure data is transmitted over electromagneticwaves. In one or more embodiments, the tire pressure data is transmittedover radio frequency waves. In one or more embodiments, the tirepressure data is transmitted by varying an acoustical impedance of themovable transponder. In one or more embodiments, the method furthercomprises testing for an acoustical impedance minimum of the movabletransponder. In one or more embodiments, the testing comprises:measuring a first acoustical impedance of the movable transponder at afirst frequency of the ultrasound energy; measuring a second acousticalimpedance of the movable transponder at a second frequency of theultrasound energy, the second frequency greater than the firstfrequency; and when the second acoustical impedance is less than thefirst acoustical impedance, measuring a third acoustical impedance ofthe movable transponder at a third frequency of the ultrasound energy,the third frequency greater than the second frequency. In one or moreembodiments, the testing further comprises: measuring a first acousticalimpedance of the movable transponder at a first frequency of theultrasound energy; measuring a second acoustical impedance of themovable transponder at a second frequency of the ultrasound energy, thesecond frequency greater than the first frequency; and when the secondacoustical impedance is greater than the first acoustical impedance,measuring a third acoustical impedance of the movable transponder at athird frequency of the ultrasound energy, the third frequency lower thanthe second frequency. In some embodiments, the testing occurs while thevehicle is in motion.

IN THE DRAWINGS

For a fuller understanding of the nature and advantages of the presentinvention, reference is made to the following detailed description ofpreferred embodiments and in connection with the accompanying drawings,in which:

FIG. 1 illustrates an exemplary electro-acoustic power pad;

FIG. 2 depicts an exemplary abstraction of an electroacoustic chargingsystem comprising electroacoustic power pad and portable deviceelectroacoustic receiver;

FIG. 3 illustrates an exemplary adaptive power supply to anelectroacoustic charging system;

FIG. 4 illustrates an exemplary electroacoustic transducer mechanicalalignment stage;

FIG. 5 illustrates an exemplary receiver module an electroacousticcharging system;

FIG. 6 demonstrates the selective activation of an exemplary transducerarray of an electroacoustic charging system;

FIG. 7 is the top down view of an exemplary transducer array of anelectroacoustic charging system;

FIG. 8 projects an isometric view of an exemplary two-dimensionalultrasonic transducer array of an electroacoustic power pad for thepurposes of charging in a non-mechanical alignment environment;

FIG. 9 depicts an exemplary temporal abstraction of the side view of2-dimensional electroacoustic phased array and corresponding wavefrontsteering for non-mechanical alignment;

FIG. 10 illustrates an abstraction circuit used to produce electricalsignals delivered to 2-dimensional electroacoustic phased arrays;

FIG. 11 illustrates the side view of an exemplary electroacousticcharging cover circumscribing a generic portable device;

FIG. 12 depicts top and side views of an exemplary electroacousticcharging system comprising electroacoustic power pad and portabledevices;

FIG. 13 depicts top and side views of an exemplary electroacousticcharging system comprising electroacoustic power pad and portabledevices according to an alternate embodiment;

FIG. 14 illustrates in-situ autonomous sensor charging of anelectroacoustic system in a modern automobile according to an additionalembodiment of the present invention;

FIG. 15 illustrates a cutaway and diagrammatic view of a rim and axlethat includes a direct tire pressure monitoring system (DTPMS) thatincludes one or more ultrasonic transducer components according to oneor more embodiments;

FIG. 16 illustrates a block abstraction of an electroacoustic DTPMScomprising a stationary transceiver and a movable transponder accordingto one or more embodiments;

FIG. 17 illustrates a detailed cutaway of the non-rotating member of thesuspension system and break rotor to illustrate the path of ultrasoundenergy between the stationary transceiver and the movable transponder,according to one or more embodiments;

FIG. 18 illustrates a movable transponder that includes a pressuresensor for measuring the air pressure of a tubeless tire according toone or more embodiments;

FIG. 19 illustrates a movable transponder that includes a pressuresensor for measuring the air pressure of a tubed tire according to oneor more embodiments;

FIG. 20 is a flow chart for designing a testing apparatus andtransmitter driver and mapping the parameter field of a DTPMS accordingto one or more embodiments;

FIG. 21 is a flow chart for designing a testing station and transmitterdriver and mapping the parameter field of the stationary transceiveraccording to one or more embodiments;

FIG. 22 is a flow chart for optimizing the ultrasound energy transferfrom the stationary transceiver to the movable transponder according toone or more embodiments;

FIG. 23 is a flow chart for dynamically optimizing the ultrasound energytransfer from the stationary transceiver to the movable transponderwhile the movable transponder is in motion according to one or moreembodiments; and

FIG. 24 is a cutaway and diagrammatic view of a shock absorber of avehicle suspension system that includes that includes one or moresensors coupled to ultrasonic transducer components according to one ormore embodiments.

DETAILED DESCRIPTION

Aspects of this application are directed to the transmission ofelectrical power between electronic devices without the use of wires.More specifically, some aspects of this application pertain to thetransmission of electrical power between a charging pad and electronicdevices using ultrasound to overcome the aforementioned limitationsenumerated in the background. One or more embodiments or implementationsare hereinafter described in conjunction with the drawings, where likereference numerals are used to refer to like elements throughout, andwhere the various features are not necessarily drawn to scale.

Other aspects hereof are directed to a novel electroacoustic chargingsystem of portable devices. However, it is not beyond the scope of thepresent invention to apply ultrasound recharging or direct power to manysmall consumer appliances where suitable. These include ultrasonictoothbrushes, battery powered hearing aids, and a variety of electronicdevices such as cell phones, pads, and notebook computers. In thecommunication data device field, the present concepts can be applied toreceivers, transmitters, transceivers, including those that arenetwork-enabled such as Web-enabled to carry out communications of anypresently known or equivalently understood format.

Another embodiment includes a portable, compact, lightweight power packthat can be placed in a conventional bag, purse, pocket or similarpersonal container for transporting to wherever the power delivery isneeded.

Unlike electromagnetic radiation, ultrasound requires a medium fortransmission, such as solids, air, gases, liquids, and liquid-ladengels. At frequencies above 100 kHz, it is significantly absorbed by airwhich limits the efficacy of its propagation. On the other hand,ultrasound propagation can be highly directional over short distances.Ultrasound, being a pressure wave, will not interfere withelectromagnetic transmissions of nearby electronic devices in anyfrequency band. Ultrasound mitigates the exposure of electromagneticradiation to the body. Although there is a dearth of research, someconjecture high intensity cell phone radiation may have negative effectson tissue of the brain. Ultrasound power transmission into tissue isreviewed by U.S. Pat. No. 8,082,041 (Radziemski), which is herebyincorporated by reference in its entirety.

Ultrasound can be used to recharge batteries or capacitors (UltraSoundElectrical Recharging—USer™) or to provide power directly to a device(UltraSound Electrical Power transfer—Usep™), both of which the presentapplication is applicable to. Convenient charging of batteries for smallelectronics remains problematic, particularly in the area of cell phoneswhere quotidian use requires frequent recharging. The appearance ofvarious charging methods on the market, including electromagneticinduction chargers from Panasonic, Qualcomm, et al. is evidence of anunmet technological need which the present invention addresses, inaddition to pocket chargers such as the Halo2Cloud. Other aspects ofthis application are directed to a system that transmits electricalpower from a first unit to a second unit using ultrasound to power asensor coupled to the second unit. In a specific example, the foregoingsystem is a DTPMS. Such a system can overcome one or more of thelimitations described in the background.

FIG. 1 illustrates an exemplary electro-acoustic power pad 100. Althoughonly a single portable electronic device 110 is depicted, multipledevices, such as cellular telephones, are able to be chargedsimultaneously. The current examples are intended to be generalizebeyond just cell phones, including to other mobile computing orentertainment or communication devices, etc., generally “personal datadevices”. Described in greater detail later in the disclosure,electroacoustic power pad comprises a charging surface 120 which matesthe transmitter transducer 130 with the receiver transducer 140 which isdisposed within the portable electronic device 110. The ultrasoundreceiver is contained within a receiver unit which may be external toportable electronic device 110 or integrated therein during fabricationof the electronic device 110.

The distance between the transmitter and receiver transducers 130, 140may be zero (in contact) or up to 10 cm. Charging surface 120 maycomprise one or more transfer media. The medium may be a liquid, solid,gas, or gel suitable for acoustic transmission. The front, flat face ofthe charging surface 120 may be approximately parallel to the front,flat face of the proximal to the receiver transducer 140. In anotherembodiment, curved faces are used to enhance focusing effects thatameliorate power transfer. In other embodiments, the distance betweenthe transmitter and receiver transducers 130, 140 may be up to 100 cm ormore, depending on the application, the ultrasound frequency, powerdelivered to the transmitter transducers 130 and, most importantly,acoustic medium.

FIG. 2 depicts an exemplary block abstraction of an electroacousticcharging system 200 comprising electroacoustic transmitter 210 andelectroacoustic receiver 225. Electroacoustic transmitter 210 comprisespower source 280, active power adaptor 275, transmitter controller 270,signal generator 230, amplifier 235, transmitter interface 240,transmitter transducer 245 and electromagnetic antenna 260. As will bediscussed in greater detail with respect to FIG. 3, power source 280 canbe direct or alternating current with active power adaptor 275 havingthe capacity to handle both.

Transmitter controller 270 maintains command over numerous components ofelectroacoustic transmitter 210 either by pre-programming or activefeedback loop using user set or predetermined parameters. Transmittercontroller 270 sets the output current and voltage egressing from activepower adaptor 275. Transmitter controller 270 then proceeds to set theoutput (frequency, magnitude, phase, etc.) of signal generator 230.Signal generator 230 can a variable frequency oscillator or asynthesized signal generator or other suitable waveform generatingdevice, such as an LC circuit.

After setting the predetermined ultrasonic frequency, transmittercontroller 270 amplifies the electrical signal via amplifier 235 andtransmitter interface 240. Electroacoustic power levels can be setmanually by an input command or be placed under the control of afeedback loop which keeps it at the predetermined value. A usefulfeedback parameter, whose value is relayed from the electroacousticreceiver 225 to the transmitter controller 270, is the power received atthe ultrasonic receiver transducer 250. This information is transmittedover electromagnetic communication between antennae 260, 265. Typically,it would be desirable to keep the output power stable for optimumoperation of the device for the purpose of direct power. However, forbattery 220 charging purposes, particularly in conjunction of modernlithium ion batteries, it is desirable to vary the power as a functionof discharge.

Another important function of the transmitter controller 270 is tomonitor and change the frequency of the ultrasound in order tocontinuously maximize the power delivery. Typically, the range ofchanges due to temperature are approximately 10% of the resonantfrequency. Compensation is achieved via signal generator 230 or othermethods which are well known to those skilled in the art. Again, thefrequency can be set manually with an input command, or can be placedunder the governance of the transmitter controller 270 utilizing inputthe feedback loop.

EA receiver 225 comprises battery 220, rectifier 215, receivercontroller 285, receiver interface 290, receiver transducer 250 andelectromagnetic antenna 265. In the present embodiment, battery 220 is alithium ion battery. However, any chemical storage battery, such as leadacid, is suitable. In other embodiments, power storing capacitors arenot beyond the scope of the present invention.

In operation, receiver transducer 250 and receiver interface 290converts ultrasonic acoustic energy 255 to electrical power. Electricalpower retains the shape of the transmitted waveform of ultrasonicacoustic energy 255 and needs to be transformed via rectification so asto be useful for battery 220 charging. Rectifier 215 is an electricaldevice that converts alternating current (AC), which periodicallyreverses direction, to direct current (DC), which flows in only onedirection. In one or more embodiments, rectifier 215 may comprise on ormore of the following: vacuum tube diodes, mercury-arc valves, copperand selenium oxide rectifiers, semiconductor diodes, silicon-controlledrectifiers and other silicon-based semiconductor switches.

In the present embodiment, rectifier 215 also comprises voltageregulation circuitry for maintaining battery 220 voltage by receivercontroller 285. Within the receiver unit 225 are components for wirelesscommunication to electroacoustic transmitter 210. These parameterscomprise the disposition of battery charge, sensor location andtemperature, and the load and state of the device being charged.

FIG. 3 illustrates an exemplary adaptive power supply 275 to anelectroacoustic charging system. Adaptive power supply 275 determineswhether ingressing power is derived from a DC source 310, AC source 340or combination thereof, such as a sine wave with a DC offset. Whenutilizing power from DC source 310, adaptive power supply 275 convertsto a voltage determined by transmitter controller 270 using a DC-DCtransformer, such as, a step down, buck boost or other suitable powertransistor circuitry. In one embodiment, AC source 340 is 120V, 60 Hz.AC signal is processed through rectifier 320 in accordance with priorrectification discussion. It then can either be manipulated by regulator330 or routed through DC-DC transform circuitry, both of which achievethe same result at output 345.

FIG. 4 illustrates an exemplary electroacoustic transducer mechanicalalignment stage 420 disposed between electroacoustic transmitter andreceiver units 430, 435. Piezoelectric element 440 is placed on thefront face of electroacoustic receiver unit 435 which converts theacoustic energy to electrical and transferred to receiver output 445.Alignment is achieved by inserting acoustic coupling medium 425 intomechanical alignment flanges 415. The transmitter transducer 420transmits acoustic energy of waveforms comprising continuous or pulsedwidth with variable duty cycle, pure sine waves, square waves,triangular waves or an arbitrary repetitive shape.

Acoustic coupling medium 425 can be a gel pad, ultrasound coupling pad,liquid, or a gas. The primary criterion in choosing an acoustic couplingmedium is matching acoustic impedance(s) so that power transmission ismaximized with a low loss material. Exclusion of air is also desiredbecause air attenuates (lossy) ultrasound over frequencies of 100 kHz.Charging pad surface 410 maintains relatively parallel geometries foralignment.

FIG. 5 illustrates the feedback loop of an exemplary receiver module 500an electroacoustic charging system. Receiver module 500 compriseselectroacoustic receiver controller 560, graphic user interface 520,regulator/rectifier 550, output power monitor 510, sensor inputs 590,receiver transducer 530 and electromagnetic antenna 505. Data iscollected and stored as parameters which is then transmitted overelectromagnetic antenna 505 as an electromagnetic signal 580. Thefeedback loop is used to maximize acoustic power transmission 540 andmonitor the health of the circuit. Power is monitored 510 and displayedat the GUI 520.

FIG. 6 demonstrates the selective activation of an exemplary transducerarray of an electroacoustic charging system 600. In the presentembodiment, feedback looping is used to activate transducers which areproximal to portable devices for charging. As can be seen, portabledevice 610 is being charged through receiver transducer 640 fromtransmission transducers 650-651. Portable device 620 is receivesacoustic power through receiver transducers 641, 642 via transmissiontransducers 653-654. Portable device 630 is receives acoustic powerthrough receiver transducers 643, 644 via transmission transducers657-659. To conserve power, transducers 652, 655 and 656 are notactivated.

FIG. 7 is the top down view of an exemplary transducer array 700 of anelectroacoustic charging system with an exaggerated receiver transducer710 in accordance with the present embodiment. There are two geometricalissues affecting alignment of a transmitter to the receiver in both theelectromagnetic and ultrasound methods. The first is lateral translationover the receiver. The second is angular misalignment between thetransmitter and receiver. The use of an array transmitter enablescompensation for both of these misalignments. The voltage, currentand/or power out of the receiver is a signal fed back to the externalcontroller which commands the array transmitter to search for theoptimum alignment. In another embodiment, an imaging ultrasound systemis added to the transmitter unit to provide the feedback on the depthand orientation of the receiver, thereby assisting alignment. This maycompensate for misalignment but may not search for a receiver in somedesigns.

FIG. 8 projects an isometric view of an exemplary two-dimensionalultrasonic transducer array 820 of an electroacoustic power pad 800 forthe purposes of charging in a non-mechanical alignment environment. Inone or more embodiments two dimensional arrays are used for the purposesof non-mechanical alignment. A phased array is an array of transducersin which the relative phases of the respective signals feeding thetransducers are varied in such a way that the effective radiationpattern of the array is reinforced in a desired direction and suppressedin undesired directions.

To keep the temperature of a device within tolerances, a cooling devicesuch as a circulating-liquid heat exchanger may be provided. One or morePeltier coolers, miniature high-capacity fans, or other methods can beattached to or nearby the transmitter/receiver assembly. Temperaturesensing devices within the transmitter and receiver may relaytemperatures to the external controller, which will then apply thecorrect power to the cooling device in order to keep the temperature ofthe transmitter and receiver unit, and application under charge at safevalues.

Piezoelectric elements of the transmitter and receiver may be monolithicelements of piezo ceramics, composite materials, polymers or otheremerging materials. They may be one- or two-dimensional arrays of smallpiezoelectric elements of the same variety of materials. CapacitivelyMachined Ultrasound Transducers (CMUTs) or other mechanisms for inducingultrasound vibrations are an alternative to conventional piezoelectricelements. In one embodiment, a 2-dimensional array can be used toprovide non-mechanical alignment of transmitter and receiver in responseto optimization signals generated within the receiver unit and relayedback to the transmitter.

In one environment, high temperatures, CMUTS are especially attractive,because temperatures of over 150 C can cause piezoelectric elements tofail. CMUTS can withstand temperatures up to 800 C and severalatmospheres of pressure. So they are attractive options for enginecompartment environments. They can also be easily made into arrays thatcan be used for wavefront steering.

FIG. 9 depicts an exemplary temporal abstraction of the side view of2-dimensional electroacoustic phased array 920 and correspondingwavefront steering for non-mechanical alignment. In the presentembodiment, signals 930 propagating from phased array 920 aredifferentiated by a constant phase 910. The result is a beam steeredacoustic wavefront 940, which can be directed towards a portable devicefor the purposes of charging.

For angular alignment two effects are considered. The first of these isthe turning of the beam's wave front from parallel to the face of thetransmitter array, through an angle that makes the wave front parallelto the face of the receiver. This compensates for angular misalignmentof the faces of the two transducers. For two dimensional surfaces thisneeds to be done along two axes. It is well known to those skilled inthe art that this is accomplished by embedding a constant timedifferential, which results in a phase difference, between each elementof the array.

FIG. 10 illustrates an abstraction circuit used to produce electricalsignals delivered to 2-dimensional electroacoustic phased arrays. Clock1010 supplies a timing standard to phase shifters 1025-1035. Relativephase is received from beam position and feedback controller 1080 andsent to amplifiers 1060 which are tied to power supply 1020. Theamplified signals drive acoustic transducers 1050 in accordance with thelatest embodiment. Transmitted power information 1040 is scanned andcommunicated back to beam position and feedback controller 1080 throughelectromagnetic antenna 1070. Phase can then be adjusted to maximizetransmitted power to portable device.

FIG. 11 illustrates the side view of an exemplary electroacousticcharging cover 1100 to be used with any generic portable device 1110.Electroacoustic charging cover adapts to any generic portable device1110 using its charging port (e.g., USB) 1140 through theelectroacoustic charging cover 1100 interface 1130. Charging or directpower is accomplished through piezo element and conversion circuitry1120.

In an aspect, the present concepts may be applied to an existing marketwhich needs retrofit batteries; in another aspect, the present conceptsmay be applied to a market where ultrasonic rechargeable batteries areintegrated into the fabrication process of phones. The ability to add aretrofit battery pack to any cell phone can be useful. The battery packcontains piezoelectric elements that convert mechanical stress toelectrical energy. The small pack sends the electrical energy to thebattery inside the cell phone. This can eliminate the need to replaceexisting cell phone batteries with piezo batteries. Again, those skilledin the art will appreciate that the present exemplary device of acellular phone can equally be generalized to cover other personal datadevices such as personal digital assistants, gaming devices,communication platforms and mobile computers and tablets. In otherwords, electroacoustic elements that convert mechanical energy toelectrical energy are designed within the battery packs, to whichexisting personal devices can be connected. Other personal data devicesmay have incorporated within them, the electromechanical receiverelement or elements as well as the associated circuitry, which isactivated by an external matched transmitter source.

FIG. 12 depicts top and side views of an exemplary electroacousticcharging system comprising electroacoustic power pad 1210 and cellphones 1230, 1220. Cell phones 1220, 1230 have piezo receiver elements1240, 1250 integrated therein. Charging pads can be of sizes toaccommodate one, two, or several devices at a time. The upper side viewshows the latter case which the transmitter pad is made up of manyindependent piezo elements. These sense when a receiver is over them.Only those elements are then active. This keeps power requirements lowand reduces heating of the pad and device. A soft cover can be used toavoid air in the interface with receiver. The charging pad housestransmitter elements, electronics and connection to a wall plug forinput power. A pad that could accommodate several small appliances wouldbe from 4 to 6 inches wide and from 6 to 8 inches long. and ½ to 1 inchthick. One inch square comprises approximately 20 to 45 such piezos. Inanother embodiment the entire pad comprises a single ultrasoundproducing element. This can be a piezoelectric material, CMUTS orflexible polymer PVDF.

FIG. 13 depicts top and side views of an exemplary electroacousticcharging system comprising electroacoustic power pad 1300 and portabledevices 1310 according to an alternate embodiment. Portable devices 1310are inserted into charging ports 1340 and held in place with softsprings whereby they are acoustically coupled to ultrasonic transducers1420 through coupling media 1330. The present configuration is desirabledue to the exclusion of air at the boundary layer.

When a device is placed on the pad, the transmitter elements send outultrasound signals, and powers up the receiver, which returns a signalto the pad indicating it is there. The proper transmitter elements arethen activated to perform charging. Alternately a proximity switchsenses where the phone or battery is on the pad and piezos are activatedonly around the device. This way power is not lost when all piezos areactivated. Only the ones around the device are activated. Then a signalgoes from receiver to transmitter when the battery is fully charged.

FIG. 14 illustrates in-situ autonomous sensor charging of anelectroacoustic system 1400 in a modern automobile according to anadditional embodiment of the present invention. In the automobileindustry, ultrasound power delivery will decrease costs and increasesafety. Ultrasound recharging may be a power saving method in caseswhere sensors 1410, 1420, 1430 and transmitters are close to oneanother. However, the ability of recharging without running wires, likein car or truck doors, will save manufacturers money and reducemaintenance issues. Another embodiment attaches a stage via a slightsuction generated by a boot and clamp method, as used for affixing itemsto the inside of an automobile windshield. A manual adjustment method,in one embodiment, uses three screws of fine pitch set in a triangle,which aligns the platform transmitter angularly over the receiver.

According to one embodiment, low-frequency ultrasound is used toilluminate one or more receivers in vibrational energy. The onlylimitation on the ultrasound frequency is its ability to penetrate a fewfeet of air without significant absorption. The receivers would convertvibrational energy into electrical energy. This is stored near thesensors or used in real time and functions like an RF-ID system. A fewacoustic transmitters strategically positioned in places in the enginecompartment, trunk and body can deliver power to a majority of thesensors of interest. The acoustic transmitters are powered from the mainautomotive battery or the power train itself. The availability ofsignificant amount of power for transmitters will compensate forreceiver inefficiencies. Issues of personnel safety can be avoided byappropriate placement of the transmitters, avoiding for examplepropagating through the auto's passenger compartment.

FIG. 14 illustrates a cutaway of an auto 1400 with a variety of sensors1410-1440 and receivers/transceivers (triangles) that pertain to thesuspension and steering. The sensors and receivers may be in closeproximity to one another. Or, the receivers may be tethered to thesensors and in a location more favorable to reception of the incomingultrasound. Illustrated are the possible placements of a few ultrasoundtransmitters (diamonds) that may provide power to several sensorssimultaneously. In one embodiment, the ratio of the frequency and sizeof the transmitters will be chosen so that the ultrasound is emittedover a large cone angle that contains the receivers of several sensors.Because ultrasound transducers can be made thin, less than 5 mm inthickness, they can fit up against flat panels in the compartments wherethey are mounted.

In the oil and gas industry, recharging batteries for undersea sensorsor other applications is expensive requiring waterproof connections forthe recharging lines, and dangerous because electrical rechargingequipment can cause sparks which could lead to fires or explosions.Underwater compliant contact connections can be used with ultrasound totransmit to a receiver without an electrical connection and wirelessly,increasing safety and reducing cost.

FIG. 15 illustrates a cutaway and diagrammatic view of a rim and axlethat includes a direct tire pressure monitoring system (DTPMS) 1500 thatincludes one or more ultrasonic transducer components, as describedherein. The DTPMS 1500 includes a stationary transceiver 1510 thatincludes at least one transmitter acoustical element 1511 and a movabletransponder 1520 that includes at least one receiver acoustical element1521. The transmitter and receiver acoustical elements 1511, 1521 can beor can include a piezoelectric material or element.

The stationary transceiver 1510 is mounted on or attached to anon-rotating member 1530 of the wheel suspension system, such as anaxle. The stationary transceiver 1510 is disposed at a location close orproximal to wheel hub 1540. In one example, the stationary transceiver1510 is disposed about 5 cm to about 30 cm from wheel hub 1540. Inanother example the stationary transceiver 1510 is disposed about 10 cmto about 25 cm from wheel hub 1540, about 15 cm to about 20 cm fromwheel hub 1540, or any value or range between any two of the foregoingvalues. As used herein, “about” means plus or minus 10% of the relevantvalue or number. The stationary transceiver 1510 can be powered by alocal battery unit or by the vehicle's main battery. The movabletransponder 1520 is mounted on or attached to the wheel rim 1550 by astrap 1525 where it is exposed to the internal tire pressure of a tubedor a tubeless tire (not illustrated) mounted on the rim 1550. The strap1825, which can securely pull a first side (e.g., an unexposed side) ofmovable transponder 1520, such as a first side of a movable transponderhousing, against the wheel rim 1550 so that the first side of movabletransponder 1520 is in direct physical contact with the wheel rim 1550to receive ultrasonic energy transmitted by stationary transceiver 1510.The wheel rim 1550 is mounted on break rotor 1560, which is as arotating part of the wheel hub 1540.

In operation, stationary transceiver 1510 generates ultrasound energythough transmitter acoustical element 1511, which travels through thenon-movable member(s) 1530 of the wheel suspension system, break rotor1560, and wheel rim 1550 to receiver acoustical element 1521 where it isconverted into electrical energy, which is used to power one or moresensor(s) 1522 on the movable transponder 1520. Thus, the movabletransponder 1520 operates as a power adaptor to transform acousticalenergy into electrical energy for the sensors 1522. In some embodiments,the ultrasound energy generated by stationary transceiver 1510 forms astanding wave pattern as a function of the ultrasound energy frequency.In some embodiments, the stationary transceiver 1510 is configured togenerate a standing wave pattern of ultrasonic energy such that themovable transponder 1520 is located at a high-energy node of standingwave to enhance or maximize energy transfer to the movable transponder1520. One skilled in the art will understand that standing waves can beformed on two-dimensional surfaces (e.g., on a Chiandi plate) as well ason or in three-dimensional surfaces, such within a structure of avehicle as described herein. In general, a standing wave patternprovides regions of high and low amplitude energy (e.g., nodes andantinodes, respectively).

In some embodiments, the stationary transceiver 1510 is configured togenerate progressive longitudinal waves and/or shear waves of ultrasonicenergy. The standing wave, progressive longitudinal waves, and/or shearwaves of ultrasonic energy are transmitted through the solids (metaland/or non-metal solids) and liquids/gel-like media (e.g., lubricants,coupling media, etc.) in the vehicle between stationary transceiver 1510and movable transponder 1520. In general, the ultrasonic energy does notpass through the surrounding air due to the impedance mismatch at thesolid-air (or liquid/gel-like media-air) boundary.

The sensors 1522 can measure the tire pressure, temperature, wheelimbalance, gas composition, or other property of the tire or wheel. Insome embodiments, the sensor(s) 1522 include a pressure sensor diaphragmdisposed on an exposed face 1523 of stationary transceiver 1510. Themovable transponder 1520 transmits the data sensed by the sensor(s) 1522to stationary transceiver 1510, which is in electrical communication,directly or indirectly, with the vehicle's control system 1575. The datacan be transmitted (e.g., digitally) through a variety of means, forexample RF transmission or keyed acoustical impedance changes of theultrasound energy harvesting by movable transponder 1520. The sensor(s)1522 can operate continuously (e.g., in real-time) or in an intermittentmode. Likewise, the movable transponder 1520 can transmit the dataobtained from sensor(s) 1522 continuously (e.g., in real-time) or in anintermittent mode. Alternatively, the movable transponder 1520 canacquire and/or transmit data from a first sensor continuously butacquire and/or transmit data from a second sensor in an intermittentmode. In addition or in the alternative, the movable transponder 1520can push data to stationary transceiver 1510 on a continuous or on anintermittent basis, or the stationary transceiver 1510 can poll/pulldata from the movable transponder 1520 on a continuous or intermittentbasis.

The vehicle's control system 1575 includes a central processing unitthat can analyze the received data, display some or all of it to themotorist, and generate an alarm if the received data is out of anoperating tolerance window, or greater or lower than a predeterminedthreshold value. For example, if the received data indicates that thetire pressure is lower than a predetermined value (e.g., less than 25psi), the vehicle's control system 1575 can generate an alarm. In someembodiments, the predetermined value is variable based on the internaltemperature of the tire, which can be monitored by one of sensors 1522or another sensor. For example, the predetermined threshold value fortire pressure can be about 25 psi to about 35 psi (or any value or rangetherebetween) when the tire is cold (e.g., less than about 75 deg. F.)but it can be higher (e.g., about 30 psi to about 40 psi, or any valueor range therebetween) when the tire is hot (e.g., greater than about120 deg. F.). The predetermined threshold value for tire pressure can behigher or lower depending on the vehicle. For example, larger passengervehicles, such as full-size pickups and sport utility vehicles, can havea higher predetermined threshold value for tire pressure, such as about30 psi to about 45 psi (or any value or range therebetween), when thetire is cold, and about 35 to about 55 psi (or any value or rangetherebetween) when the tire is hot. In another example, thepredetermined threshold value for tire pressure can be up to about 115psi when the tire is cold for large trucks, such as tractor trailers,semi-trailers, construction vehicles, etc.

Each wheel/tire of the vehicle can be equipped with its own DTPMS 1500so each tire can be monitored individually in the manner describedabove. Using ultrasound transmitted through the solid metal members 1530of the suspension and wheel system addresses some or all of the problemsof conventional direct TPMSs, as discussed above, and can add thepotential for more comprehensive sensing and monitoring in real-time. Inaddition, the moveable transponder 1520 described herein does notrequire a battery, which may be subject to drain or failure, thusenhancing the reliability of the system. For example, moveabletransponder 1520 can receive energy from stationary transceiver 1510continuously, thus obviating the need for a battery. In someembodiments, moveable transponder 1520 includes a capacitor or othertemporary energy-storage device that can temporarily store energy, whichmay be needed in case of a short or momentary lapse in energy transferfrom stationary transceiver 1510. The stationary transceiver 1510 can bepowered by the vehicle's main battery, by a separate battery unit, orcontinuously from electrical power generated by the vehicle'salternator.

The stationary transceiver 1510 and movable transponder 1520 can includesome or all of the components and function(s) of electroacoustictransmitter 210 and electroacoustic receiver 225, respectively, asdiscussed above, with the exception that moveable transponder 1520includes a capacitor (or other temporary energy-storage device) in placeof battery 220, for example as described below with reference to FIG.16.

FIG. 16 illustrates a block abstraction of an electroacoustic directtire pressure monitoring system (DTPMS) 1600 comprising a stationarytransceiver 1610 and a movable transponder 1620. The stationarytransceiver 1610 and movable transponder 1620 include the same orsimilar components as electroacoustic transmitter 210 andelectroacoustic receiver 225, respectively, as discussed above, with theexception that moveable transponder 1620 includes a capacitor 1602 inplace of battery 220. The capacitor 1602 can store a quantity of energyto power the moveable transponder 1620 for a brief period, such during amomentary blackout or brownout. In some embodiments, capacitor 1602 is afilter capacitor that forms a portion of rectifier 215. In otherembodiments, capacitor 1602 is a separate and distinct component fromrectifier 215. In some embodiments, power source 1680 is the vehicle'sbattery, a separate battery unit, or the vehicle's alternator.

In addition, stationary transceiver 1610 and movable transponder 1620can be the same as or similar to stationary transceiver 1510 and movabletransponder 1520, respectively.

FIG. 17 illustrates a detailed cutaway of the non-rotating member 1530of the suspension system and break rotor 1560 to illustrate the path ofultrasound energy between the stationary transceiver 1510 and themovable transponder 1520. As illustrated, a plurality of bearings 1700are disposed between the non-rotating member 1530 and break rotor 1560.Each bearing 1700 includes a rolling bearing element 1710 disposedbetween an inner race 1720 and an outer race 1730. The inner race 1720is attached to non-rotating member 1530 and the outer race 1730 isattached to break rotor 1560. A thin film of lubricant 1740 is disposedaround the rolling bearing element 1710 to provide lubrication thereto.The thin film of lubricant 1740 can have a cross-sectional thickness ofabout 1 micron or less. In other words, there can be about 1 micron orless of lubricant 1740 between rolling bearing element 1710 and innerrace 1720 and about 1 micron or less of lubricant 1740 between rollingbearing element 1710 and outer race 1730.

As can be seen, ultrasonic energy can be transmitted between eachcomponent of the foregoing, which provides a continuous physical mediumfor ultrasonic energy to pass between (e.g., to/from) stationarytransceiver 1530 and movable transponder 1520 (not illustrated). Forexample, ultrasonic energy generated by stationary transceiver 1530 canbe transmitted to movable transponder 1520 along a path 1750. The path1750 extends from stationary transceiver 1510 through non-rotatingmember 1530, inner race 1720, lubricant 1740, rolling bearing element1710, lubricant 1740, outer race 1730, and break rotor 1560 to movabletransponder 1520. As discussed above with respect to FIG. 15, movabletransponder 1520 is mounted on wheel rim 1550, which is mounted on breakrotor 1560.

FIG. 18 illustrates a movable transponder 1820 that includes a pressuresensor 1822 for measuring the air pressure of a tubeless tire 1800. Themovable transponder 1820 is attached to or mounted on wheel rim 1850 bya strap 1825, which can securely pull a first side (e.g., an unexposedside) of movable transponder 1820, such as a first side of a movabletransponder housing, against the wheel rim 1850 so that the first sideof movable transponder 1820 is in direct physical contact with the wheelrim 1850 to receive ultrasonic energy generated by a stationarytransceiver.

The pressure sensor 1822 is disposed on a second side (e.g., an exposedside) of movable transponder 1820, such as a second side of a movabletransponder housing. The pressure sensor 1822 can include a pressuresensor diaphragm in some embodiments. As illustrated, the pressuresensor 1822 is exposed to the internal pressurized cavity 1805 definedby tubeless tire 1800 and thus can directly measure the air pressure oftubeless tire 1800. Movable transponder 1820 and pressure sensor 1822can be the same as, similar to, or different than movable transponders1520, 1620 and pressure sensor 1522, described above.

FIG. 19 illustrates a movable transponder 1920 that includes a pressuresensor 1922 for measuring the air pressure of a tubed tire 1900. Themovable transponder 1920 is attached to or mounted on wheel rim 1950 bya strap 1925, which can securely pull a first side (e.g., an unexposedside) of movable transponder 1920, such as a first side of a movabletransponder housing, against the wheel rim 1950 so that the first sideof movable transponder 1920 is in direct physical contact with the wheelrim 1950 to receive ultrasonic energy generated by a stationarytransceiver.

The pressure sensor 1922 is disposed on a second side (e.g., an exposedside) of movable transponder 1920, such as a second side of a movabletransponder housing. The pressure sensor 1922 can include a pressuresensor diaphragm in some embodiments. As illustrated, the pressuresensor 1922 senses pressure exerted by tube 1910 of tubed tire 1900. Forexample, tube 1910 can press against pressure sensor 1922 (e.g., apressure sensor diaphragm), which allows pressure sensor 1922 to measurethe internal air pressure of tube 1910. Movable transponder 1920 andpressure sensor 1922 can be the same as, similar to, or different thanmovable transponders 1520, 1620, 1820 and pressure sensors 1522, 1822described above.

FIGS. 20-23 are flow charts that illustrate different aspects ofconfiguring a DTPMS to generate ultrasound energy that provides adesired standing wave, progressive longitudinal waves, and/or shearwaves of ultrasonic energy. FIG. 20 is a flow chart 2000 for designing atesting apparatus and transmitter driver and mapping the parameter fieldof a DTPMS. The physical construct of a piezo-electrictransmitter-receiver for energy transfer as well as detailed modalanalysis can be numerically simulated using one of several commercialmodeling tools, such as those available from The MathWorks, Inc. (e.g.,MATLAB®), COMSOL Inc. (e.g., COMSOL Multiphysics®), ANSYS, Inc., andothers. In addition, the physical can be modeled numerically to generatethe optimal energy transfer, based on a series of source-receiverconditions, while including different intervening layers of media.

In step 2010, an ultrasonic energy driver for the stationary transceiveris designed according to one or more inputs, such as the range ofoptimal node spacing of the desired standing wave of ultrasonic energy(and/or other desired properties of progressive longitudinal wavesand/or shear waves of ultrasonic energy). The design determined in step2010 includes a desired frequency range for the ultrasonic energy, theoperating power levels of the ultrasonic energy, the type or form of theultrasonic transducers. The design determined in step 2010 can alsoinclude the form of ultrasound energy transmission (e.g., standing wave,progressive longitudinal waves, shear waves, or a combination of any ofthe foregoing). After the ultrasonic energy driver is designed orprovided, the operating parameters are characterized in step 2020. Forexample, in step 2020, the operating frequency range and power levels ofthe ultrasonic energy are systematically scanned.

In one example, the characterizations in step 2020 can occur when thestationary transceiver and the movable transponder of the DTPMS aremounted on the appropriate locations on the vehicle, as described above.In another example, the characterizations in step 2020 can occur whenthe stationary transceiver and the movable transponder of the DTPMS aremounted on a bench apparatus, for example on a steel plate, to model theexpected behavior of the system. The stationary transceiver can thenscan through its potential range of operating ultrasound frequencies ateach of its operating power levels. The parameters of the DTPMS can thenbe measured and logged, such as the resonance frequencies of thevehicle, the node distribution of the standing wave produced at eachfrequency and power level, and the amount of ultrasound energy that themovable transponder can harvest. Other parameters can include theproperties of the progressive longitudinal waves and/or shear waves ofultrasonic energy, the resultant energy transfer, and other parameters,if progressive longitudinal waves and/or shear waves of ultrasonicenergy transfer are used instead of or in addition to standing waves.The result of step 2020 is a data table that includes the foregoingparameters. A data acquisition system can be connected to or inelectrical communication with the movable transponder to collect theforegoing data.

In the example of a standing wave pattern of ultrasound energy transfer,this parameter data provides a general map of the standing wave patternin the vehicle in the vicinity of the DTPMS (e.g., along path 1750) orin the bench test sheet. The standing waver pattern is a function of theultrasound frequency and resonance frequency of the materials throughwhich the ultrasound energy passes (e.g., bench apparatus or componentsof the vehicle in the vicinity of the DTPMS, such as along path 1750).Specifically, there will be resonance frequencies where the wave pattern“stands” and does not change over time. At frequencies different fromresonance frequencies the modes will be “stirred” meaning they willrapidly change over time with the result that no clear patterns emergeand the sheet vibrations appear chaotic. This is an undesirablecondition as the amplitude at “nodes” will be comparatively small,rendering the energy transfer process less efficient. In contrast, atresonance frequencies, there will form well-defined nodes and troughs ofvibrational modes. The spacing of these nodes will shrink as thefrequency is increased. Evaluating the pattern change with frequency andtransmitting transducer shape and size will be part of mapping out theparameter field. Scanning through the amplitude of the energizingultrasound energy into the transmitting transducer will initially besubstantially linear but may become non-linear at a higher power.

In addition or in the alternative, the parameter data provides a generalmap of the progressive longitudinal wave and/or shear wave pattern(s) inthe vehicle in the vicinity of the DTPMS (e.g., along path 1750) or inthe bench test sheet, which can be used to optimize energy transfer.

FIG. 21 is a flow chart 2100 for designing a testing station andtransmitter driver and mapping the parameter field of the stationarytransceiver. In step 2110, a suitable transmitter driver is designed.The transmitter driver can be based on one or more inputs, such as therange of optimal node spacing and the ultrasound energy powerrequirement. These inputs can be provided based on the parameterscollected and analyzed in step 2020.

In step 2120, the stationary transceiver is mounted in a vehicle ormounted on a bench apparatus, such as a steel plate, to simulate avehicle. The movable transponder is not mounted in step 2120. Thestationary transducer is then scanned through its operating frequencyrange and power levels to characterize the system. Examples ofdata/parameters collected are resonance frequencies and nodedistributions, as measured with a testing apparatus. In someembodiments, the testing apparatus can also measure the ultrasonicenergy that can be harvested at each frequency and power level at thelocation of the testing apparatus (e.g., on the wheel rim or on thebench apparatus).

The output of step 2120 is a parameter data table of the system'simpedance in an unloaded state (i.e., without the movable transponder inplace). This can serve as a reference to compare the unloaded system toa loaded system where the movable transponder is in place.

FIG. 22 is a flow chart 2200 for optimizing the ultrasound energytransfer from the stationary transceiver to the movable transponder. Instep 2210, the DTPMS system is set up, preferably mounted on a vehicle,as described above. In step 2220, the stationary transceiver cyclesthrough a plurality of ultrasound energy frequencies at a minimumoperating power level to measure the system impedance and to determinean impedance minimum while the movable transponder is in a stationaryposition. With the movable transponder in place, the system impedancecan change from the impedance measured in 2120. In general, a lowerimpedance represents a stronger energetic coupling while a higherimpedance represents a weaker coupling.

If an impedance minimum is not found in step 2220, the power of thestationary transceiver is incrementally increased at step 2230 and thestationary transceiver again cycles through a plurality of ultrasoundenergy frequencies at the increased power level. This process continuesuntil an impedance minimum is found. When an impedance minimum is found,the flow chart 2200 proceeds to step 2240 to establish two-waycommunication between the stationary transceiver and the movabletransponder. The stationary transceiver can form an ultrasound signalmodulated with an echo-request packet. The modulation may be one of thecommon analog modulation schemes such as amplitude modulation (AM),frequency modulation (FM), phase modulation (PM), quadrature amplitudemodulation (QM), space modulation (SM), single sideband modulation (SSB)or one of the common digital modulation schemes, such as amplitude shiftkeying (ASK), asymmetric phase-shift keying (APSK), continuous phasemodulation (CPM), frequency-shift keying (FSK), multiple frequency-shiftkeying (MFSK), minimum-shift keying (MSK), on-off keying (OOK),pulse-position modulation (PPM), phase-shift keying (PSK), quadratureamplitude modulation (QAM), single-carrier frequency-division multipleaccess (SC-FDMA) or trellis coded modulation (TCM). Some of thesemodulation schemes require more than one transmitting source and wouldtherefore only be applicable when the stationary transceiver and/or themovable transponder includes a plurality of transducers. Theeffectiveness of the modulation schemes can vary as understood by thoseskilled in the art. Alternatively, the stationary transceiver cancommunicate using electromagnetic signals. When the movable transponder,which is programmed to listen and respond to specific commands orrequests, responds then communication is established. If not, an errorflag should be raised.

As discussed above, communication from the stationary transceiver to themovable transponder can be facilitated through a modulation scheme ofthe ultrasound energy. The movable transponder demodulates (e.g.,through hardware and/or software) the transmitted ultrasound energy todetermine the signal(s) or command(s) communicated thereby.Communication from the stationary transceiver to the movable transponderoccurs through impedance changes “seen” by the movable transponder. Tofacilitate this direction of the communication, the movable transpondercan be enabled, through hardware and software engineering, to modulatethe load that the movable transponder presents to the stationarytransceiver. The impedance may then be varied according to any of theabove-mentioned modulation schemes, if deemed suitable. As discussed,the stationary transceiver is enabled, through hardware and softwareengineering, to demodulate the seen impedance changes. In someembodiments, the foregoing can be achieved or supplemented bytheoretical and/or numerical analyses.

FIG. 23 is a flow chart 2300 for dynamically optimizing the ultrasoundenergy transfer from the stationary transceiver to the movabletransponder while the movable transponder is in motion. Afterbi-directional communication with the movable transponder has beenestablished and power transfer has been optimized while remainingstationary in flow chart 2200, a loop process may be implemented tomaintain optimal power transmission during varying operating conditions.For example, a first operating condition can be when the vehicle is inidle (e.g., about 500 to about 1,000 RPMs). A second operating conditioncan be when the vehicle is accelerating (e.g., about 2,000 to about3,000 RPMs). In another example, a first operating condition can be whenthe vehicle is in idle and other operating conditions can be when thevehicle is travelling at different speeds (e.g., at 15 mph, at 30 mph,at 45 mph, at 60 mph, etc.) and/or on different road conditions (e.g.,smooth pavement, dirt road, etc.). The vibrations in the vehicle causedby the engine, the rotational speed of the wheels, the suspension,and/or the road conditions may affect the power transmission. Thus, theinitial “stationary” operating parameters (frequency, power level) fromthe first operating condition may be adjusted as illustrated in flowchart 2300 in a “dynamic tracking” process to maintain optimal powertransmission conditions even as the operating conditions change.

In step 2310, the system is tested for an impedance minimum, for exampleat an initial ultrasound frequency, which may be the same as the initial“stationary” ultrasound frequency that had an impedance minimum found instep 2220. The flow chart 2300 is a continuous loop where the ultrasoundfrequency is repeatedly or constantly being changed (i.e., decreased instep 2320 or increased in step 2330) around the optimum impedance value.If there is a change in the system that changes the optimal operatingparameters, this loop will track these changes, provided the timeconstant of the system changes are small compared to the time constantof the loop. However, since the loop may process at speeds of asubstantial percentage of the ultrasound carrier wave frequency, anypractical change in the operating conditions of the DTPMS (e.g.,stationary transceiver and/or movable transponder) may be slow comparedto the process loop speed and thus may not even be perceptible by theuser.

FIG. 24 is a cutaway and diagrammatic view of a shock absorber 2400 of avehicle suspension system that includes that includes one or moresensors coupled to ultrasonic transducer components, as describedherein. A first sensor system 2405 includes an ultrasound transceiver2410 and an ultrasound transponder 2420. The transponder 2420 includesone or more sensors 2422 electrically coupled thereto. The sensors 2422can measure various properties of high-pressure gas chamber 2425 ofshock absorber 2400, such as its pressure and/or temperature. Theultrasound transceiver 2410 and ultrasound transponder 2420 are disposedon opposing sides of tubular housing 2450 of shock absorber 2400.Tubular housing 2450 can be formed of or can include steel or othermaterial as known in the art. Tubular housing 2450 provides a physicalmedium through which ultrasonic energy can pass between the ultrasoundtransceiver 2410 and ultrasound transponder 2420, similar to theembodiments described above. In some examples, ultrasound transceiver2410 and/or ultrasound transponder 2420 generate a standing wave (and/orprogressive longitudinal waves and/or shear waves) of ultrasound energythat optimizes power transfer and that provides a carrier wave that canbe modulated to transmit information or commands. For example,ultrasound transponder 2420 can convert ultrasound energy received fromultrasound transceiver 2410 to provide electrical energy for the sensors2422 coupled to ultrasound transponder 2420. The data from sensors 2422can then be transmitted from ultrasound transponder 2420 to ultrasoundtransceiver 2410 generate ultrasound energy by modulating ultrasoundenergy waves generated by ultrasound transponder 2420.

A second sensor system 2460 is also illustrated in FIG. 24. The secondsensor system 2460 includes an ultrasound transceiver 2470 and anultrasound transponder 2480. The transponder 2480 includes one or moresensors 2482 electrically coupled thereto. The sensors 2482 areconfigured to measure one or more properties of oil reservoir 2475, suchas its temperature and/or the volume of oil in the oil reservoir 2475.Energy transfer and communication between ultrasound transceiver 2470and ultrasound transponder 2480 is the same as or similar to the energytransfer and communication between ultrasound transceiver 2410 andultrasound transponder 2420, described above.

As can be seen, the foregoing first and second sensor systems 2405, 2460allow the vehicle to monitor certain locations and properties of theshock absorber 2400 that could not be monitored using conventionalsystems. For example, conventional systems that communicate usingelectromagnetic wireless signals could not pass such signals throughtubular housing 2450 which is generally formed of steel. In addition,conventional systems require a battery to power the transponders andsensors, but the remote location of transponders 2420, 2480 would makebattery replacement impractical.

Though the foregoing figures have illustrated sensor systems formeasuring tire pressure and or measuring properties of a shock absorber,it is noted that these are just exemplary locations for such sensorsystems. Thus, the ultrasonic-powered sensors can be located in otherlocations in the vehicle (e.g., in or proximal to the exhaust system,the cooling system, etc.) or in other systems, such as industrialsystems, airplanes, etc. In addition, the term vehicle can includepassenger vehicles, trucks, construction equipment, motorcycles, andother self-propelled vehicles, whether powered by gasoline, electricity,or a combination thereof. Another application of the foregoing systemsis in underwater vehicles, boats, submarines, etc.

Ultrasound spans a large range of frequencies, from roughly 20 KHz outto hundreds of MHz. Frequencies below about 100 kHz are characterized byless absorption in air, larger ultrasound transmitters, longerwavelengths and wider cone angles into which the ultrasound istransmitted. The latter can be reduced by using arrays of transmittersemitting coherently, which also can be used to turn or focus ultrasoundradiation. However these arrays will tend to be bulky. Frequencies above100 kHz are characterized by being strongly absorbed by air, have morecompact transmitters, more collimated radiation in the near andmid-fields, and shorter wavelengths.

While the former regime is appealing for the prospect of transmittingwireless power through air to many receivers, it also brings upquestions of safety because people will be irradiated by the generallyuncollimated beams. Also because the radiation will typically be emittedinto a cone some 10 or 20 or more degrees in angular width, much of thetransmitted power will miss receivers, requiring high powertransmitters, so that some energy is incident on small receivers, againbringing up the issue of safety. Small electronics that have incidenthigh power vibrational amplitudes could be damaged. Hence any scheme forultrasound delivery through air in locations where humans are generallypresent may be rejected on the basis of safety and its effect on peopleand materials.

Some embodiments use frequencies in the 500 kHz to 1 to 2 MHz range.Other embodiments apply ultrasound in a range between 20 kHz and 100kHz, depending on the application at hand. Also advantageous will becharging geometries that bring the transmitter close to the receiver,within 1 cm or less, with the two possibly separated by a thin flexiblepad that excludes air. This type of arrangement ensures that noultrasound radiation escapes the charging path and that much lowertransmitted powers can be used because there is little power lost inside lobes. Narrowing this band of frequencies or choosing specificsmall frequency bands will depend on details of construction thatminimize reflections, match ultrasound impedances for the materials usedand optimize useful power transfer.

The present system and method may be applied to powering or chargingautomobile sensors at frequencies in the sub-100 kHz range, avoidingtransmission into the driver/passenger compartment, thereby eliminatingsafety or electronic interference issues. Other applications hereof maybe in underwater vehicles and systems. The ultrasound energy maypropagate in these applications through liquid filled bladders, and thenwirelessly to the device or battery under charge or power.

The embodiments described and illustrated herein are not meant by way oflimitation, and are rather exemplary of the kinds of features andtechniques that those skilled in the art might benefit from inimplementing a wide variety of useful products and processes. Forexample, in addition to the applications described in the embodimentsrelating to power transmission and conversion for use in batterycharging, those skilled in the art would appreciate that the presentdisclosure can be applied to any electroacoustic direct powertopologies. However, it is to be appreciated that the present exemplaryembodiments are also amenable to other like applications.

The present invention should not be considered limited to the particularembodiments described above, but rather should be understood to coverall aspects of the invention as fairly set out in the attached claims.Various modifications, equivalent processes, as well as numerousstructures, materials and unforeseen technologies to which the presentinvention may be applicable, will be readily apparent to those skilledin the art to which the present invention is directed upon review of thepresent disclosure. The claims are intended to cover such modificationsand equivalents.

What is claimed is:
 1. A direct tire pressure monitoring system for avehicle, comprising: a stationary transceiver configured to be mountedon a non-rotating axle of a suspension system for a wheel on thevehicle, the stationary transceiver comprising: one or moreelectroacoustic transmitting elements; a signal generator; an amplifier;and a first antenna; a movable transponder configured to be mounted on arim of the wheel, the movable transponder comprising: one or moreelectroacoustic receiving elements; a tire pressure sensor; and a secondantenna; wherein said first and second antennae are in electromagneticcommunication and said electroacoustic transmitting and receivingelements are in ultrasonic communication.
 2. The system of claim 1,wherein the stationary transceiver is configured to be in electricalcommunication with a central processing unit of a vehicle control systemfor the vehicle.
 3. The system of claim 1, wherein signals are generatedby said signal generator and amplified by said amplifier, said amplifiedsignals are transmitted over said one or more electroacoustictransmitting elements, said one or more electroacoustic transmittingelements generating acoustic energy that passes from said stationarytransceiver to said moveable transponder via said non-rotating axle andsaid rim.
 4. The system of claim 3, wherein said transmitted ultrasonicsignals are received by said electroacoustic receiving elements.
 5. Thesystem of claim 4, wherein the movable transponder converts saidtransmitted ultrasonic signals into converted electrical energy.
 6. Thesystem of claim 5, wherein the tire pressure sensor and ancillaryelectronics are powered by said converted electrical energy.
 7. Thesystem of claim 1, wherein the stationary transceiver is configured togenerate progressive longitudinal waves, shear waves, or a combinationthereof of ultrasonic energy.
 8. The system of claim 1, wherein thestationary transceiver is configured to generate a standing wave ofultrasonic energy.
 9. The system of claim 8, wherein a high-energy nodeof the standing wave is disposed at the movable transponder.
 10. Amethod for directly monitoring tire pressure in a vehicle, the methodcomprising: generating ultrasound energy with a stationary transceivermounted on a non-rotating axle of a suspension system for a wheel in thevehicle; receiving the ultrasound energy with an electroacousticreceiving element in a movable transponder mounted on the wheel; in themovable transponder, converting the ultrasound energy into convertedelectrical energy; and with a tire pressure sensor coupled to themovable transponder, monitoring the tire pressure of a tire mounted onthe wheel, the tire pressure sensor receiving at least some of theconverted electrical energy.
 11. The method of claim 10, furthercomprising generating a standing wave of the ultrasound energy with thestationary transceiver.
 12. The method of claim 11, further comprisingaligning a high-energy node of the standing wave of the ultrasoundenergy with a location of the movable transponder.
 13. The method ofclaim 10, further comprising wirelessly transmitting tire pressure datafrom the movable transponder to the stationary transceiver.
 14. Themethod of claim 13, wherein the tire pressure data is transmitted overelectromagnetic waves.
 15. The method of claim 14, wherein the tirepressure data is transmitted over radio frequency waves.
 16. The methodof claim 10, wherein the tire pressure data is transmitted by varying anacoustical impedance of the movable transponder.
 17. The method of claim10, further comprising testing for an acoustical impedance minimum ofthe movable transponder.
 18. The method of claim 17, wherein the testingcomprising: measuring a first acoustical impedance of the movabletransponder at a first frequency of the ultrasound energy; measuring asecond acoustical impedance of the movable transponder at a secondfrequency of the ultrasound energy, the second frequency greater thanthe first frequency; and when the second acoustical impedance is lessthan the first acoustical impedance, measuring a third acousticalimpedance of the movable transponder at a third frequency of theultrasound energy, the third frequency greater than the secondfrequency.
 19. The method of claim 17, wherein the testing comprises:measuring a first acoustical impedance of the movable transponder at afirst frequency of the ultrasound energy; measuring a second acousticalimpedance of the movable transponder at a second frequency of theultrasound energy, the second frequency greater than the firstfrequency; and when the second acoustical impedance is greater than thefirst acoustical impedance, measuring a third acoustical impedance ofthe movable transponder at a third frequency of the ultrasound energy,the third frequency lower than the second frequency.
 20. The method ofclaim 19, where the testing occurs while the vehicle is in motion.